List.Add is changing existing members?

This is a discussion on List.Add is changing existing members? within the C# Programming forums, part of the General Programming Boards category; I'm using the .Add() method of the .NET List to add new members. Trouble is, this seems to be changing ...

  1. #1
    Registered User
    Join Date
    Feb 2010
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    3

    List.Add is changing existing members?

    I'm using the .Add() method of the .NET List to add new members. Trouble is, this seems to be changing all existing members to be the same as the added one.

    This a problem anyone has come across before?

    Console screenshot

    And here's the offending code, with my debug output code either side:

    Code:
                    System.Console.WriteLine("\nWhat I'm adding: ");
                    System.Console.WriteLine(bufferCentroid.ToString());
    
                    centroids.Add(bufferCentroid);
    
                    System.Console.WriteLine("List contains: ");
                    for (int k = 0; k < centroids.Count(); k++)
                    {
                        System.Console.WriteLine(centroids[k].ToString());
                    }

  2. #2
    Registered User NeonBlack's Avatar
    Join Date
    Nov 2007
    Posts
    435
    centroids.Add(bufferCentroid);
    Simply adds a reference to the list, and since you're re-using the same reference, all items in the list point to the same object. What you want to do is actually create new objects (using new).
    I copied it from the last program in which I passed a parameter, which would have been pre-1989 I guess. - esbo

  3. #3
    Registered User
    Join Date
    Feb 2010
    Posts
    3
    Aha!

    Thanks.

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